The Whitehouse has announced that President Obama's National Security Advisor is resigning and he will be replaced by Susan Rice, the U.S. Ambassador to the United Nations. NPR's Ron Elving is here to tell us more. Ron, some months ago, Ms. Rice was rumored to be nominated Secretary of State - that, of course, did not happen. So why don't you give us a quick fill on the back story.

RON ELVING, BYLINE: Susan Rice was inline, as they say, to be the Secretary of State last fall when the president was re-elected, but she was immediately the focus of tremendous criticism and controversy because of the attack, back in September of 2012 in Benghazi, Lybia. She was the first person to go out and speak for the administration, regarding that attack, and she portrayed it as a public demonstration, a protest riot that got out of hand and led to the deaths of four Americans in Benghazi. Later, of course, everyone - everyone learned, and she acknowledged, that it had been, in fact, a planned terrorist attack. So despite all of the caveats that she might have given at that time, she was seen as going out and making excuses, she was seen as protecting the Obama Administration, politically, and she became the flashpoint, the lightening rod, for all the criticism of the Obama Administration on the Benghazi incident and she has remained so, even until now.

WERTHEIMER: But this new job Ms. Rice has, is an important job. Does that mean that they - the specter of Benghazi is no longer hanging over her head or is not necessarily going to follow her throughout her career?

ELVING: As we have seen, the specter of Benghazi does not go away. It remains a fascination and a focal point for many people in the Congress, particularly among Republicans, and in the conservative movement in general. So as this high profile person - in many people's minds, the second most important person in the foreign policy establishment, the National Security Advisor - she is going to remain a symbol to all those who are still concerned about what the administration did and said about Benghazi. But, this is an important difference between this job and Secretary of State or any cabinet job, in this position, Susan Rice does not need to be confirmed by the United States Senate.

WERTHEIMER: Now, She replaces Tom Donilon as the president's principle advisor on foreign policy, how is his tenure regarded? Do you imagine that much will change?

ELVING: Tom Donilon is best known, perhaps, as someone who ran a very tight ship, who was very well organized, super-well prepared; briefed the president hundreds of times on foreign policy issues; had a hand in the entire Osama bin Laden operation when that number one world terrorist was killed by American forces; and now has been associated, strongly, with what's called the pivot to Asia - the re-focusing of the Obama administration's foreign policy, away from the war on terror, away from Europe, away from the entire Middle East, and towards the emerging relationships with China, and Japan and Korea. This week, President Obama is meeting with the Chinese president. This is an unusual meeting, perhaps an unprecedented meeting, with no, really, set script; where the two are going to sit down in California, they're going to have a face to face meeting. That is seen, largely, as engineered by Tom Donilon, and his crowning achievement.

WERTHEIMER: So Donilon, and, presumably, also, Susan Rice, will be at that meeting. Susan Rice's job at the United Nations - who takes her place?

ELVING: Her place will be taken by Samantha Power. Samantha Power is a young, 42 year old academic and journalist who has been associated with Barack Obama since he was a senator a decade ago; and who has been, also, a writer, has won the Pulitzer Prize for one of her several books; and has also been closely associated with the issue of genocide and human rights. That is something that has made her very simpatico with Susan Rice as they've worked together in the first Obama term, and now as a United States ambassador to the United Nations. If she is confirmed by the Senate, she would be expected to focus on those human rights issues that have been a long-standing part of the American agenda in the United Nations.